Model Output Discussion:

[swebby]

Hi Blue Army,

And a nice control run too again! :lol:

Do you know what exactly is tweaked each time between all the members?

Is it always the same tweaks to the same members?

Also, why not just run all of them (with tweaked initial data on all bar the op) on a higher resolution and get shot of the control? Why have a lower resolution at all?

Never quite fully got my head around the ensembles.

I imagine it takes alot of data number crunching to run a high resolution run, remember they are global models not just covering Europe. So if you ran 20 high res runs, or in the case of ECM, 50 high res runs, thats an awful lot of computing power needed. So, I think that is why the ensembles are run at lower res, due to computing constraints as mentioned.

I may well be wrong but i've always assumed that the ensembles are there for the purpose of verifying the control/op runs? That is - If we tweak the data does the output stay with the high res run (therefore the output can be assumed to be robust) or does it throw up completely different synoptics and therefore we should have a low confidence in the main output. If this is their purpose then there is no real need to run at high res if there are constraints on processing resources. I sometimes feel a little too much credence is given to individual ensemble members on here because they show a favourable outcome (eg very cold) rather than looking at the divergence/scatter relative to the main output.

Funnily enough i glanced at the GEFS 06 runs today and have seen very good agreement for the next 7-10 days, then read GP’s thoughts where he suggested that the models may well struggle! Given GP’s track record so far this winter i know where i would place my money. Even with good agreement nothing should be taken as gospel.

Cheers

S

[snowmadchrisuk]

Good job they're not perfect otherwise we'd have nothing to discuss. No more ramping no more baiting no more phantom bartletts etc etc...

Have you got a link to noaa about the assemblies would be an interesting read.

Sure :

http://www.emc.ncep.noaa.gov/gmb/ens/info/ens_detbak.html

Chris

[Harsh Climate]

Just checked the charts and the UKMO + ECM is fantastic, while the GFS is absolutly dire!!

Hopefully there might be a big turnaround by the gfs later, to something more like the ecm . If there was that would really highlight how fickle the gfs esembles can be sometimes!

[SP1986]

I would argue not just how fickle the ensembles are but how fickle the whole set of models are. None of them can be trusted at the moment

[PB22]

Interesting model output so far today, although I am dubious of the ECM 00z run. Its rare to see the ECM do such a flip. The ECM ensembles for London (more useful than Holland funnily enough!) show the operational was actually one of the colder options in FI for our shores, which is no real surprise:

http://www.meteogroup.co.uk/uk/home/weather/services/ensemble_forecast.html

Nonetheless, there has been an increase in the number of cold runs appearing again.

The 12z UKMO will be one to watch this evening as it may well have picked up on something and given its steady consistency over the last few days it seems to be more reliable to watch at the moment, although it undoubtedly helps that it only goes out to T+144.

[Optimus Prime]

GEM is hideous for cold;

No surprise I'll be backing the GFS and GEM on this one.

[The PIT]

LOL ECM back to winter now with the GFS style output from several days ago. Well nearly. So if GFS flips back the ramping will start once again.

[cooling climate]

Interesting model output so far today, although I am dubious of the ECM 00z run. Its rare to see the ECM do such a flip.

I think what was more odd was the ECM flipping to mild in the first place after showing very cold ensembles

for so long. The ECM 0z run this morning is much more beliveable in my opinion. Not long now to find out

how much support the other models give it.

Edited February 1, 2010 by cooling climate

[Bobby]

GME is an improvement on earlier...

http://91.121.94.83/modeles/gme/run/gme-0-108.png

[igloo]

I think what was more odd was the ECM flipping to mild in the first place after showing very cold ensembles

for so long. The ECM 0z run this morning is much more beliveable in my opinion. Not long now to find out

how much support the other models give it.

the two euro models are by far superior models to the the rest of the cannon fodder if they are picking up on something cold in the next 6-7 days it is far more believable in my opinion

[Bobby]

GFS +84

Much better, nice undercut.

OK probably not much better, but better.

[PB22]

the two euro models are by far superior models to the the rest of the cannon fodder if they are picking up on something cold in the next 6-7 days it is far more believable in my opinion

Indeed, and if the UKMO picks up on something then I will be more interested!

[snowmadchrisuk]

The 12z looking better so far , the Important thing is Lows are starting to head SE instead of directly East.

[cooling climate]

Game on according to the t96 GFS chart, that leaves the UKMO and I would be

very surprised if it showed anything different now.

Not much of a mild spell either from what I can see.

I would not be at all surprised if the GFS is being over progressive with the low coming off

the eastern US seaboard at t48. The ECM 0z is slower with this and if so everything

will be even further west and a colder pattern would develop earlier.

Edited February 1, 2010 by cooling climate

[Rollo]

It begins to look like our milder spell will be very limited-as to the beasterly,only time will tell.

[PB22]

Ahhh, we might be getting somewhere now...UKMO looks "interesting" at T+96 this evening:

The T+120 and T+144 charts will be most interesting....

[sandstorm2]

Very big changes on the 1200 GFS in comparison to yesterday, when will we know the truth.

Can any of the more informed give an explanation, I really thought the block was going to get blown away by the atlantic.

SS2

Edited February 1, 2010 by sandstorm2

[Bobby]

The beast is back

+144 GFS 12z

Edited February 1, 2010 by Barb-

[PB22]

UKMO T+120:

Now we're talking...this has got my interest now.

P.S. Shiver, stop copying posts to you know where please. Thanks.

[Cecil Hogmanay Melchett]

UKMO T+120:

Now we're talking...this has got my interest now.

P.S. Shiver, stop copying posts to you know where please. Thanks.

Yes Paul it would appear ukmo has backtracked somwhat!!

Lets see where we are going but the raging Atlantic is cancelled.

:lol:

EDIT UKMO is super. :lol:

Edited February 1, 2010 by happy days

[sandstorm2]

Looking at the 1200 GFS 850's look surprisingly high especially when they were so low just a couple of days ago.

SS2

[Iceberg]

Yep, 12Z GFS has the required pattern at 144, with the tilt and weakness in the spainish/med to act as a pressure release and the undercut....

The 120Z from the UKMET GM is even more of a backtrack and just lets the lower undercut at will.

So cold and cold from both models.

[nick sussex]

OMG I can't cope with any more drama! the UKMO holds the trough much further west and this really helps,the GFS has it much further east, could this be the reverse zonal winds coming to our aid! At 144hrs the UKMO brings us back to earth as it cant decide which block to go with, anyway its a start at least so lets see what the ECM has to say.

Edited February 1, 2010 by nick sussex

[PB22]

UKMO T+144:

Clearly its a developing story, but its an interesting run from the UKMO tonight, and its very important to have UKMO on board IMO. :lol:

[Snow Queen one]

I have a question? How come the charts are so different i have been looking at the GFS and the diff on the 12z to the 06z is just weird which one of the runs is wrong do you think?